The historical pantodapoi were the most basic and numerous infantry of the Non-Balkan Diadochoi states, such as Arche Seleukeia and the Ptolemaioi. Drafted from numerous nationalities in a manner somewhat similar to the multinational Persian army of the old that Megas Alexandros defeated, the Pantodapoi made rather poor soldiers, not unexpected given their lack of armor in general and poor equipment. Of course, this meant that the pantodapoi were readily available.
Similarly, even with the robust line of supply that the Arche often boasted, in some cases light levies were necessary, especially in planets like Anatole which was frequently invaded by Tropas Libre and Asia Eater raiders to supplement the preexisting garrison provided by the Arche. For the case of Anatole, most pantodapoi are levied by the local governor, and are usually equipped with weapons fit for reserves and training forces. Nonetheless, the pantodapoi usually pulled more than what was invested in them, largely because the Pantodapoi often took advantage of the heavy defensive guns located at fortifications.
As for the Spheres, the term is rather ambiguous, as the Volunteers (Peripolai) also fit in with the definition of lightly armed infantry, and given the lack of conscription amongst the Spheres, that could not be a definitive dividing factor between the peripolai and the pantodapoi, and in fact, the term is often used interchangeably.